1. Field of the Invention
The present invention relates to a stock oil composition for preparing a carbonaceous material for a negative electrode of a lithium-ion secondary battery capable of achieving high charge and discharge capacity.
2. Description of the Related Art
A lithium-ion secondary battery has lighter weight and more excellent input and output characteristics than a conventional secondary battery such as a nickel cadmium battery, a nickel hydrogen battery and a lead battery, and has therefore been considered promising in recent years as a power source for an electric vehicle and a hybrid vehicle. A carbonaceous material is used as an active material constituting an electrode of a lithium-ion secondary battery and has been extensively studied with the aim of increasing the performance of a lithium-ion secondary battery (refer to, for example, Japanese Patent No. 3056519 and Japanese Patent Application Examined Publication (JP-B) No. 4-24831/1992).
The carbonaceous material used as a negative electrode material of a lithium-ion secondary battery is, in general, roughly classified into a graphite-based carbonaceous material and an amorphous carbonaceous material. The graphite-based carbonaceous material has an advantage of higher energy density per unit volume compared with the amorphous carbonaceous material. For this reason, the graphite-based carbonaceous material is usually employed as a negative electrode material in a lithium-ion secondary battery for a cellular phone and a laptop computer which are compact but require large charge and discharge capacity. Graphite has a structure in which hexagonal network planes of carbon atoms have been stacked regularly, and during charging and discharging, intercalation or deintercalation of lithium ions takes place at the edges of the hexagonal network planes.